US3553521A
Expired / Lapsed
US
⏱️ 0.0 years remaining
Indirectly heated cathode for an electron discharge tube with an insulated heating element
Assignee: US Philips Corp
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Filing: 1968-01-29
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Granted: 1971-01-05
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Expires: 1988-01-29
Abstract
Abstract An indirectly heated cathode for electron discharge tube having a refractory metal support, e.g. molybdenum or tungsten, the inner surface of which is coated with a thin layer of a metal of the platinum group to minimize oxidation of the refractory metal. The cathode is insulated from a heating element by a layer of alumina which surrounds the heating element.
Inventors
- 👤 Marinus Antonius Maria Bakker
- 👤 Johannes Christiaan Duran
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-10-28 14:51
CPC Classifications
H; H01; H01J; H01J1/00; H01J1/02; H01J1/13; H01J1/20; H01J1/24; H01J1/26
Claims Analysis
Total Claims: 3
Claim 1
Independent Claim
70 words
An indirectly heated cathode for an electron discharge tube provided with a heating wire which is insulated by means of a metal oxide from a support for an emissive layer, at least the surface of this support facing the heating wire consisting of molybdenum, said surface having thereon a layer of at least one of the metals of the platinum group having a thickness of at least 3 Mu .
Claim 2
Dependent Claim
70 words
An indirectly heated cathode for an electron discharge tube provided with a heating wire which is insulated by means of a metal oxide from a support for an emissive layer, at least the surface of this support facing the heating wire consisting of molybdenum, said surface having thereon a layer of at least one of the metals of the platinum group having a thickness of at least 3 Mu .
Claim 3
Dependent Claim
21 words
A cathode as claimed in claim 1, wherein the heating wire has a layer of a metal of the platinum group.
References Cited (Backward Citations)
US2733378A
Cited
US1719988A
Cited
US2878410A
Cited
US3283195A
Cited
US3268305A
Cited
US3401297A
Cited
USPTO Annuity & Maintenance Windows
| Annuity Stage | Window Opens | Payment Deadline | Surcharge Period Until | Estimated Fee | Status |
|---|---|---|---|---|---|
| 3.5 Years (Year 4) | 1974-01-04 | 1974-07-06 | 1975-01-05 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1978-01-04 | 1978-07-06 | 1979-01-05 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1982-01-04 | 1982-07-06 | 1983-01-05 | $7700.00 | Window Closed / Lapsed |